dreyfus

When I first purchased my '07 I ran it for a thousand miles at a 93 octane, then a thousand miles at 87, then back to 93, then back to 87. I kept detailed mileage records and noted perceived performance, taking both long trips (500+ miles) and short.

The result? No difference in mileage or performance or engine noise (knocking) nor anything else I could detect. I'm sure a dynometer would pick up a difference, but for my day-to-day driving experience there was none.

I've used 87 octane almost exclusively for five years now. My ES350 currently has over 96,000 miles on it and runs just fine.

Lew270

NJLexes I have aslo seen similar statements both on the forum and external web research that states certain Toyota models use the same engine...I wonder...if the owner of a Avalon put 91 in his tank, would that car now produce 272HP as opposed to 268HP (not that it matters to the original reason for this post)...but just curious

NJLEXES

I would tend to think not. Reasoning is that the different timing settings in the Lexus ES350 which are optimized for PREMIUM FUEL are already programmed in and would scale back if lower octane fuel is detected.
On the flip side, the TOYOTA models rated at 268hp were not designed with PREMIUM FUEL in mind. As such, the engine can't benefit (scale up) for the increased octane.

Only possible solution would be if ECU (in a toyota) could be reprogrammed with the Lexus settings. Maybe could be done...however doubt it would be worth the cost.
Keep in mind the new ES350 (2011) is now rated at 268HP using Regular 87 octane.
No mention of Premium fuel requirement any longer.

AlGator

I believe so.

Somewhere in the Avalon owners manual I recall something about the use of premium fuel for maximum performance, (or words to that effect). Thus, in my humble opinion, further evidence that the 3.5L in the Lexus and Avalon are likely one in the same.

The ECM in conjuntion with the knock sensors are capable of advancing/retarding timing to accomodate the fuel used.

2008ES

It would be unrealistic for Lexus, or any vehicle manufacturer, to instruct the consumer to use more expensive fuel just to seem more "luxurious." The owner's manual is not written to "sell" any aspect of the vehicle. It's for people who are already owners, hence the name. The documentation is only interested in conveying operating and maintenance specifications, including fuel specs, from the engineers and designers to the end user. When the owner's manual recommends premium fuel, it means the people who designed the car recommend premium fuel for the reasons they state. If the car ran better on Chateau Margaux then they would say so in black and white. Lexus simply wants their cars to operate as intended for their customers. They do not have a side deal going with the refineries to encourage us to foolishly spend more on gasoline.

Anyone interested in getting the correct answer owes it to themselves to perform proper tests on their own. You will get no usable data from one tankful, or from 1000 miles, which is about two fill-ups. Try 100,000 miles instead. Then you will have more data over a wide range of conditions to draw some reliable conclusions. For example, every driver with an MPG display knows that MPG improves as the car warms up, and as the weather warms up.

An average American drives 15,000 miles per year. Right now, unleaded gasoline costs about $3.60 and premium costs about $3.90. A Lexus ES 350 gets an EPA estimated city/highway of 22 MPG. That's 682 gallons per year for an average ES 350 driver. If the car did not go any farther on a tank of premium versus unleaded, he would be spending about $4 more per week at the pump to burn premium:

$2,660 premium
$2,455 unleaded
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$205 annual difference ($4 per week)

That is your worst case. On the other hand, any improvement in the distance the premium tank will take you reduces the $4 difference. In my case over several years of recording mileage religiously in a very similar vehicle (the owner's manual recommended premium fuel), the difference amounted to about $1 per week, since premium gasoline did provide improved mileage. And by following the owner's manual recommendations, the car also lasted 15 years, which works out to quite a bit saved in car payments alone. I'll use that savings to buy my kid some candy bars... and a college education.

__

AlGator

Its not just to appear more luxurious, premium fuel allowed Lexus to claim the extra 4HP, setting it apart ever so slightly from the Avalon/Camry 3.5L at 268HP.

As for mileage, the Avalon gets 19/28 MPG on regular verses 19/27 in the ES 350 on premuim. However, MPG remained the same for 2011 ES 350 when Lexus wisely dropped the premium fuel recommendation.

Granted, these are miniscule differences but when added on top of already exploding gas prices every dollar the stays in our pockets rather than to OPEC is a good thing in my book.

2008ES

When the Avalon debuted, it and the V6 Camry also had a 4 horsepower difference, although the engines and fuel specs were identical in that case. The extra 4 horses came primarily from manifold tweaks to the Avalon. Just saying, there's other options the manufacturer can use to elevate a statistic if it's purely for marketing reasons. The Avalon was like 300 pounds heavier than the Camry, so I don't think the 4 horsepower was intended to convince the buyer of anything concrete. Possibly more of a psychological one-up like you suggest, since the Avalon sticker was a good bit higher than the V6 Camry's.

LexBob2

I think that in addition to the weak economy and high gas prices, competitive forces played a hand in Lexus to going to recommending regular unleaded for te ES. A lot of the competition LaCrosse, Taurus, Lincoln etc. have V6's with regular recommended.

tardorange

I was using 87 on my 2007 ES350 for a year and I had no problems. I was getting 27MPG. On my Acura TL I used 87 and I get 18MPG....so everyone is suggesting premium 93 so lets see.

My 528i uses premium 93 and gets 26MPG. The 325xi I put 87 in and it gets 25MPG.

Bottom line not much difference at least not with BMW/Lexus cars...not sure what Acuras deal is. 18MPG is horrible.

safford197

I agree with NJLexes and others. There's no issue with 87 vs 93 (the manual does use the word recommend, not required) but I can tell you when I tried it back when gas was over $4 a gallon I did the math (not just using the computer but dividing gallons/miles) and found that I was getting less MPGs which actually over took the ~7-8% savings per gallon at the pump. With that said however, back in 2009 I took a 3,400 mile road trip. I meticulously logged altitude, temperature, average speed, octane used, brand, and how many cold starts on that tank, etc... The octane made little difference as compared to brand and probably municipality. For example, Costco in Alabama netted me just over 20MPGs with premium on the highway!

As a result of that trip I fill up with 93 octane at Shell only.

Anecdotally I also feel like the lack of detergent additives may cause premature wear of the O2 sensors which could breakdown the catalytic converter prematurely too. So if you're going to keep the car a long time I don't think it's worth the chance - but as you pointed out, this is just an opinion.

Good luck.

russellh

You cannot "change" the settings on your engine, but you can use 87 octane fuel; your car has an electronic system that adjust automatically to the fuel's octane, without any input from the driver/owner.

AlGator

10% ethanol fuel may account some for the poor MPG, as well as highway headwinds.

Further, octane recommendation is 91 so blending regular or mid-grade with premium could yield additional savings.

LexBob2

I think it's interesting that both the 2007 (as well as '08-'10) and 2011 ES350 are rated by the EPA at the same 19/27 MPG.

The '07 on premium and the '11 on regular.

Milliken

Yesterday I drove for about an hour on the highway with cruise speed clocked at 110KM (about 70 miles/hr) on 93 gas. The traffic I would considered good as there were only a few times lowered to 90 km or so. Amazingly I got 6.8 Liters/100KM . I used to get 8-9 litres per 100km with my Chrysler 3.5 engine. So, the ES350 is pretty good on gas mileage. The round trip numbers were about the same, 7.0 vs 6.8 on a round trip of 200KMs total.

The funny thing is whenever I use my foot on the gas paddle, I am increasing the gas mileage number like crazy. Well, having driven for over 30 years I suddenly realised how advanced the Lexus designers are to have programmed the cruise control logic for the best gas-mileage possible. It may well be true that a guy without much concern on gas mileage uses a lot more on a 2.5 engine versus us driving a 3.5 ES!! I think we need to change our driving habbit as close to the cruise control properties as possible to save on gas. Our way of driving are being influenced by other drivers, road conditions as well as our well being for the day. Also, being alert more, I find out that leaving a safety distance in driving indeed reduces the number of braking required, a huge plus. Finally, not trying to drive the ES like a sport car makes the ride more relaxing and enjoying - that's exactly what we wanted to pay extra for a Lexus.

The extra techniques required may be to get used to using the cruise control in city driving. I find it easy enough just practice more to make it perfect. Any comments here?

So, the next move I would pump in regular gas and to report the gas mileage here driving the same section of highway the coming weekend. I would assume if the engine runs about the same, I would continue using regular gas for a month or two to see if prolonged using of regular gas has any noticeable effect - it may be surprisingly good, let's be positive....

hey, let's stop for a minute here, changing a driving habit using more cruise control, both in the city and on the highway we might just save6-10 litres of gas (no matter what kind of gas you are using) that equates to almost $10 already. The next part of the experiment if positive, then we also save another $5 bucks per filling. We are talking of a huge saving every week yet with improved fun in driving. Am I right???

Milliken

Hello all, I now have some solid figures on comparisons between using unleaded octane 91 vs 87 on a 2008 ES350 - engine has about 22,000miles on it.

I bought my ES pre-owned for a month, I have been using premium 91, about 6 full tanks already. The engine has been running perfect. My tests were to compare on a straight highway, cruising at about 110KM for 100km to read the gas mileage on using 91 versus 87. For the two tests, I was using the same section of highway, same time and weather conditions to make sure the results are as accurate as possible. There would be almost no human intervention at all.

On 91 gas, I was getting 6.8 litres/100KM. After flushing with a full tank of 87 and I took the gas mileage on tank #2 to make sure the tank was full of unleaded 87. The result on unleaded 87 is even better, a 6.6L/100KMs. Well, rather than saying 87 gives better gas mileage, I would humbly accept the gas mileage is the same for both 87 and 91 since the difference may be within experimental erros - (see photo on octane 87 here). In fact, 6.6 L/100KMs is significantly better than the Lexus published data of 7.2L/100KMs (aren't we proud to have bought the ES? Just lovely)!!! In city driving, I noticed NOTHING different on 87 versus 91, as smooth as silk. There is absolutely no knocking at all. The conclusion for now seems to be that our ES350 engine is taking 91 and 87 with a smile giving the same power output, hence same gas mileage on the same highway under test.


I know many uses the Avalon or Camry engines to generalize it to the ES350 engine. It would still be best verified on the exact ES350 engine to see how the two octane gas performed to feel comfortable with. If we accept different gas stations will give slightly different gas even if they are rated with the same octane value, our ES engine should be designed and programmed to take it all comfortably without damage or having a long term undesirable effect. Using unleaded 87 should also be anticipated in the design process or Lexus will lose a lot of money fixing our engine under warranty! This is not happening (not that I know of) for those ES350s already drinking 87 for months and years.

I am trying to do some reasoning here, on the gas path to the engine, the pump and gas line should function the same with 91 or 87. The injectors shall work the same (I assumed) even if it may not be happy with the 87, cleaning them is no sweat and we have to clean them as a routine maintenance anyway, right?? On the engine, the built-in sensors and sophisticated software should know when to adjust for differences on the octane content so we can drive without knocking. Don't forget it is a Toyota design and the ES350 is meant to be a entry level luxurious car, it better be an all around well-built vehicle.
SO WHAT IS OUT THERE THAT STOPS US FROM USING UNLEADED 87 other than ignorance and fear? If anyone here has technical background and seeing me on the wrong side, kindly point it out so we all can learn from you.

If one continues using 91 because of the fact that the extra $5 per tank isn't a problem, or believing blindly that 91 is healthier for the ES engine, or just it is better to go by the manual, then I can't agree. Like I said before, if I can pick up for my kids several Kitkats or chips every time I fill up the tank for as long as I own the ES350, I would love to - UNTIL I discover for fact that 87 is doing something wrong. Am I alone? I hope not. With so many ES owners out there and within several months we should be able to come to a more convincing conclusion based on a larger sample size.

Whoever wants to take part in testing please submit a message here so we know how many are taking part in the testing. We all know this testing is an empirical experience, obviously the more people involved the better. Can I suggest by Aug 1 which is more than 3 months time, we come back and update all with any problems or comments? Um.... I think if the sample size is large enough we can say or prove with enough confidence that we can save $5 on every fill up for all the years ahead of us owing the ES350. Thank you very much to read a longer message up to here.

Please offer help and take part in the test. Since there is no free lunch, rather than asking everywhere getting confused answers, let's do it the hard way and is the only way - based on the Lexus spirit.

Happy driving!!

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